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When flying to Las Vegas know you’re in another world the moment you step off the plane and enter the terminal. This is what you see. The waiting passengers are right next to a bank of new-generation slot machines.  No, there is no pulling of handles: they’re all electronic and replete with sounds and flashing lights:

I ubered to the hotel where the CSICon meetings are taking place, which happens to be the Horseshoe Las Vegas (for luck I suppose, formerly known as Bally’s).  The main floor is completely filled with slots roulette tables, and other venues of gambling which have been called “a tax on stupidity”:

After waiting four hours to check into my room (I spent it in the food court reading a book I’m reviewing), I finally got a place to stay. CSICon begins this morning; the website is here and you can see the schedule here. Today is mostly workshops, but tonight at 8 pm physicist Brian Cox will receive the Richard Dawkins Award,  As noted by Wikipedia, the award is

. . . . currently presented by the Center for Inquiry to an individual associated with science, scholarship, education, or entertainment, and who “publicly proclaims the values of secularism and rationalism, upholding scientific truth wherever it may lead.” They state that the recipient must be approved by Dawkins himself.

The award will be announced by CFI and Dawkins Foundation President Robyn Blumner, and then there will be a video by Dawkins explaining why Cox is getting the award, and that is followed by the formal presentation (it will be a lovely staatuette) by astrophysicist Neil deGrasse Tyson (see below).  Cox will then give a keynote address. Tyson himself got the award in 2022, and I was honored to join the panoply in 2015.

Last night a few people forgathered for dinner at Gordon Ramsey’s Steakhouse in the Paris Casino next door.  It was a lovely meal hosted by CFI.  The wine was chosen by an astrophysicist who is also an oenophile, and is far more competent than I to select the wines. Here he is instructing the waiter that the bottle he brought was, in fact, not of the vintage noted on the menu. We got another bottle:

My meal included a starter of onion soup, heavy with cheese and thick, onion-flavored broth:

And then the famous Gordon Ramsey beef wellington, which was excellent.

On Saturday, after I speak in the morning, a frew friends and I will head to what is often regarded as Vegas’s best buffet, the Bacchanal at Caesar’s Palace, across the street. You can’t consider a trip to Vegas complete without a visit to a buffet.

Here’s a tour of the Bacchanal. I plan to concentrate on the seafood: crustaceans and oysters, and fill in the gaps with the lamb and a passel of desserts.

Neutron stars and black holes are the remnants of dead stars. They typically form as part of a supernova explosion, where the outer layers of an old star are violently cast off while the core of the star collapses to form the remnant. This violent origin can have significant consequences for both the remnant and the surrounding environment.

One thing that can happen is that the remnant can get a “natal kick,” which causes the remnant to speed away from the supernova remnant. We see this with some neutron stars, where we observe the neutron star leaving the remnant at speeds of more than 800 kilometers per second. We aren’t entirely sure what causes such large natal kicks, but they aren’t uncommon. One would assume the same thing could happen for stellar black holes. In fact, given the greater intensity of a black-hole forming supernova, you might think the kick would be even larger. But recent observations suggest that sometimes a stellar black hole can form with hardly any kick at all.

The observations focus on a black hole known as V404 Cygni. It has a mass about 10 times that of the Sun and is about 8,000 light-years away. It is also a microquasar. There is a small star that orbits V404 so closely that material is captured by the black hole. The captured material has created an accretion disk and jets similar to those formed by supermassive black holes in distant galaxies. It was discovered in 1938 and is easily observed in both visible and x-rays. With a decent telescope, you could even observe it from your backyard. Needless to say, V404 has been quite well studied.

But this new work found something new. The team identified a companion star orbiting the close binary. The star has been known for a while, but it wasn’t until we had detailed observations from the Gaia spacecraft that the team could prove it orbits the other two. It takes 70,000 years for the distant companion to make a single orbit, but it is gravitationally bound to the other two. So V404 Cygni is a triple system, not a binary one. Which is a bit strange. When the black hole formed, it should have been kicked away from the system. The close companion could have hung on, but the distant companion shouldn’t still be bound. So what gives?

When the team looked at the dynamics of the system, they found the natal kick of the black hole could have been no larger than 5 km/s. In astronomical terms, that’s essentially nothing. Therefore, V404 must have had no natal kick. If it formed from a supernova explosion, that would be unlikely. To figure out this mystery, the team looked at various models that might produce such a system. Everything from highly symmetric supernova explosions to direct collapse models where the black hole formed slowly and quietly rather than with a single big boom. It turns out the quiet approach is the most likely. It seems V404 gradually accumulated material from its close companion until it just collapsed to become a black hole, and it did so quietly enough for the third companion to go along for the ride.

Reference: Burdge, Kevin B., et al. “The black hole low mass X-ray binary V404 Cygni is part of a wide hierarchical triple, and formed without a kick.” arXiv preprint arXiv:2404.03719 (2024).

The post The First Triple Star System Found Containing a Black Hole appeared first on Universe Today.

It was 1969 that humans first set foot on the Moon. Now, over 50 years later we are setting sights on building lunar bases. The ability to complete that goal is dependent on either transporting significant amounts of material to the Moon to construct bases or somehow utilising raw lunar materials. A team of Chinese researchers have developed a technique to create bricks from material that is very similar to the soil found on the Moon. The hope is that the lunar soil can in the future, be used to build bricks on the Moon.

As we step out into the Solar System the Moon is the perfect starting point. Lunar bases are an essential part in our longer term goals providing a lower gravity launch environment. With space agencies and private companies working on a sustainable presence on the Moon the prospect of a lunar base is really picking up momentum. The Artemis program hopes to return humans to the Moon by the mid 2020’s and ultimately create a permanent presence. It would serve as a scientific research location, centre for extraction of lunar material and a stepping stone for missions to Mars. 

Artist rendition of a future lunar base. (Credit: ESA – P. Carril)

Such a base would likely be built near the lunar south pole where there is plenty of water ice in the deep shadowy craters. The ice can be readily turned into drinking water, oxygen and even rocket fuel. It’s not only NASA driving this development, private companies like Space X and Blue Origin are also working on aspects of the missions. 

The team of researchers from the Huazhong University of Science and Technology have recently released a video clip revealing their results. The team led by Ding Lieyun have utilised substances similar to lunar soil to create lunar bricks that can be used to build structures on the Moon. The bricks are black and the team claim three times stronger than standard construction concrete bricks.

Five lunar soil compositions were simulated with a number of different process used to attempt to create the bricks. The different techniques will enable the team to gain sufficient scientific data to assess the viability of the different types of soil. The soil variations that the team explored simulate the different materials found near the Chang’e-5 landing site, some basaltic, others mostly anorthosite. 

A close-up view of astronaut Buzz Aldrin’s bootprint in the lunar soil, photographed with the 70mm lunar surface camera during Apollo 11’s sojourn on the moon. There’ll soon be more boots on the lunar ground, and the astronauts wearing those boots need a way to manage the Moon’s low gravity and its health effects. Image by NASA

The bricks will now be tested in a number of different ways to assess their strength and properties. They will also explore any likely degradation in the properties due to the lunar environment. The vacuum, extreme temperature changes and high levels of cosmic radiation. The bricks will now be sent to the Chinese space station aboard the Tianzhou-8 spacecraft to continue the analysis following exposure to cosmic radiation and returned by the end of 2025.

Source : Chinese Researchers Develop ‘Lunar Bricks’ for Future Lunar Base Construction

The post Building Bricks out of Lunar Regolith appeared first on Universe Today.

Millions of Americans are taking herbal remedies that may be toxic to the liver.

The post Widespread Use of Dietary Supplements Linked to Liver Damage first appeared on Science-Based Medicine.

Meanwhile, in Dobrzyn, Hili has grasped a fundamental truth:

Hili: History is happening in front of our eyes. A: What do you mean? Hili: That not everything is clearly visible.  

Hili: Historia dzieje się na naszych oczach.
Ja: Co chcesz przez to powiedzieć?
Hili: Że nie wszystko dokładnie widać.

The Free Press = Unherd = Persuasion = Reason = Tablet

The post The “Heterodox” Media: Using Groupthink and Misinformation to Inhibit Free Thought first appeared on Science-Based Medicine.

Everybody knows that for life to thrive on any world, you need water, warmth, and something to eat. It’s like a habitability mantra. But, what other factors affect habitability? What if you relaxed the conditions conducive to life? Would it still exist? If so, what would it be?

Those are interesting questions that arise as new worlds continue to be discovered around other stars. Astrobiology (the science of life on other worlds) has a general (and conservative) assumption that Earth-like environments are the best places to search. The problem is that Earth is the only place that fits that definition—at the moment. We know of approximately 6,000 exoplanets (and the number is growing) out there. Only a few come close to the Earth-like definition, which sets artificial limits on where we think life could exist.

If we widen the definition of habitability, will that expand the places we can look? What other factors should scientists consider as they search for life in the cosmos?

A recent paper titled “Self-sustaining Living Habitats in Extreme Environments”, by Harvard scientist Robin Wordsworth and Professor Charles Cockell, University of Edinburgh, examines the possibilities of specific types of organisms arising on worlds where habitability might not fit the “standard definition.” In particular, they examine the viability of photosynthetic-based simple life forms in space or on other worlds. “Our idea is to probe the limits for habitability of non-sentient life. We were able to show that there are no physical limitations on simple forms of life existing outside of planetary gravity wells, which was not a result we expected initially,” Wordsworth wrote in an email.

Questions about Life Elsewhere that Isn’t Earthlike

There’s a lot to unpack in the team’s paper, but the TL:DR summary says that life CAN exist in a variety of situations, provided certain parameters are met. And, they don’t have to be strictly Earth-like. But for the best chances, those organisms need to be photosynthetic and live in a place where sunlight from the system’s star can get through.

We only have to look at the other worlds of the Solar System to see that the standard definition isn’t going to fly for them. Venus, for example, can’t support any life on its surface. But, recent findings (and disagreements about) phosphine and warm layers in its atmosphere suggest that it could have habitable spots high above the surface. There’s no evidence that it exists in those clouds. But, they may provide a set of conditions for certain kinds of life—and those conditions don’t fit the Earthlike definition.

A composite image of the planet Venus as seen by the Japanese probe Akatsuki. The clouds of Venus could have environmental conditions conducive to microbial life. Credit: JAXA/Institute of Space and Astronautical Science

Scientists also suggest Titan, Enceladus, and Europa as possibly habitable havens for life. Again, nothing’s been found at any of them. However, it’s possible that at least Enceladus and Europa could have safe harbors for certain kinds of life. Not Earthlike, to be sure, since those forms probably wouldn’t survive there.

So, the authors ask, how much complexity do you need for life to sustain itself beyond Earth? That leads to a far more interesting question: what’s the minimum physical structure that could sustain habitable conditions on another world? Could non-sentient organisms exist in and modify different conditions?

Examining Other Parameters for Life

To answer those questions, the authors looked at various parameters, including planetary habitability, atmospheric pressure, temperature, volatile loss (from the surface and atmosphere, which also involves looking at the gravity well), radiation, free energy, and nutrients, scale and location, and maintenance and growth. All of these factors affect the rise of life and its ongoing evolution. They considered simple photosynthetic forms (that is, those that depend on photosynthesis) as a test case. That’s because, as Wordsworth points out, a solar radiation energy source is key. “When solar radiation is the energy source, life can flourish and spread over a much larger area, until its growth is limited by other things, such as availability of essential nutrients or raw materials,” he pointed out.

A schematic of the key similarities and differences between habitable worlds and a micro-organism when looking at life habitability. Courtesy Robinson and Cockell.

That reliance on solar energy is important. However, it plays much less of a role in places like Europa or Enceladus. Those two worlds do have internal energy sources or chemical energy sources, but those do not allow for photosynthesis to occur. If life exists under their ice shells, it won’t be basking in the sunlight. That’s because those surfaces are not transparent enough to allow sunlight to pass. It would have to depend on the central energy sources. That pretty much limits the areas where life can flourish. That’s not to say that it won’t exist there. It will occur under more limited circumstances than simple photosynthetic organisms arising with energy input from the star.

As a result of their research, Wordsworth and Cockell argue that non-sentient life can flourish under the proper conditions at other worlds. They found no limitations to it surviving in self-contained ecosystems elsewhere, provided those ecosystems can regulate their habitability internally. In other words, life—particularly simple forms of it—can exist under conditions that aren’t always Earthlike.

It’s Not Always About Other Planets

One other outcome of the Wordsworth-Cockell research points out benefits for other fields of study. For example, life support for humans in space. That would allow for the use of biotechnology in medicine, food, habitat construction, and spacecraft propulsion. Essentially, we could create biologically generated habitats for environments such as the Moon or Mars.

In addition, the idea that such simple life can exist in a wider variety of environments could push astrobiology to get past the idea that only Earth-like places should be the “holy Grail” of the search for life. Of course, once you assume that other places with more extreme environments can support life, you need to figure out ways to detect it. Such detections require new strategies that depend on where you’re searching and what you’re searching for.

Finally, we need to look at how much the living beings on our planet have shaped its habitability. We also need to understand what the initial conditions were that shaped life here. Then, scientists can apply that information in the hunt for life in other places. That leads to further speculation about how we could (if we wanted to), shape the biospheres of other worlds. Obviously, Mars comes to mind. That’s terraforming, and scientists continue to examine that possibility.

For More Information

Self-sustaining Living Habitats in Extreme Environments (PDF)

The post Life Can Maintain a Habitable Environment in Hostile Conditions appeared first on Universe Today.

One of the many threats facing space travellers and indeed our own planet is that of Solar Storms. At their most minor they can grant polar latitudes with a gentle auroral display but at their most extreme they can pose a threat to technology in space, communications and even our atmosphere. Now a team of researchers have found that extreme space weather can leave its mark in tree rings, leaving evidence that can help guard against future severe events. 

The term space weather is typically used to refer to the changing conditions and events occurring on the Sun that can effect the space surrounding Earth and the other planets. The events are driven by the Sun’s magnetic field and can include flares, coronal mass ejections, and the solar wind. When the events interact with our own magnetic field they can cause problems for satellite communication, GPS systems and power grids. They can also produce the somewhat enigmatic auroral displays that gently dance across the skies. 

Image of a solar flare (bright flash) obtained by NASA’s Solar Dynamics Observatory on Oct. 2, 2014, with a burst of solar material erupting being observed just to the right of the solar flare. (Credit: NASA/SDO)

Space Weather often creates energetic particles that, through the interactions of gas in the atmosphere, can produce radiocarbon (an isotope of carbon that is unstable and radioactive.) The process of growth in trees uses carbon from the air to create more wood. This is the process that leads to the creation of rings in their trunks. The team of researchers led by Amy Hessl from the Eberly College of Arts and Sciences has been exploring correlations between the annual tree rings and solar activity. 

Tree ring records date back hundreds of years and have revealed evidence of severe solar storms known as Miyake events. The events bring with them an increase in the amount of radiocarbon in the atmosphere and it is this that can be traced in trees. The first event occurred in 774AD and another in 993AD and evidence in tree rings occurred 12 years ago. To date, 7 more events have been found dating back over the last 14,000 years. 

Scientists study tree rings because they retain a record of climatic events and changes. They also record the Sun’s activity. Image Credit: Rbreidbrown/Wikimedia Commons, CC BY-SA

The space weather events are not just an inconvenience though. Humans should only receive a certain dose of radiation in their lifetime. If you’re unlucky enough to be on a high altitude aircraft flight at the time of a severe solar storm it could give you a lifetime dose of radiation in one hit. If you were in space, it would more than likely kill you!

Theories of tree growth have assumed that trees absorb radiocarbon at an even rate. The team believes that trees take up radiocarbon in a different way, in a more biased way. They even found that different trees absorb the carbon isotope differently and the same trees at different locations were also found to be absorbing differently. 

They studied different species; the evergreen conifer from Utah, bristlecone pines also from Utah, the bald cypress from Northern Carolina and oak trees preserved in a riverbed in Missouri. Core samples were taken from the cross section of trees to enable the rings to be analysed and data. Trees that were alive during one of the Miyake events would have recorded the event in the chemistry of the rings but possibly differently for different trees. 

Studying the tree rings may give us a better understanding of how trees interact with atmospheric carbon and help us to better understand how to prepare for future extreme events. Surviving such events can only be possible through advanced preparation and it is hoped the study will lay a solid foundation. 

Source : WVU researcher says ancient tree rings may help Earth prepare for dangerous space weather

The post How Bad Can Solar Storms Get? Ask the Trees appeared first on Universe Today.

This stunning image of a star cluster in the Small Magellanic Cloud (SMC) is more than just a pretty picture. It’s part of a scientific effort to understand star formation in an environment different from ours. The young star cluster is called NGC 602, and it’s very young, only about 2 or 3 million years old.

This image lives up to the standard the JWST has set. NGC 602 is inside a nebula of multi-coloured gas and dust. The many energetic stars in the cluster light the nebula up from within, while its outer edges are dark. The cluster is rich in ionized gas, which indicates that star formation is still taking place.

The cluster is different from our region of space. It’s a low-density environment and has lower metallicity than our region. Metallicity affects the heating and cooling of gas, and in general, the more metals there are, the more they absorb heat, keeping the star-forming gas cooler. Since stars form from cooler gas, metallicity is expected to enhance star formation.

But there are many questions, including how brown dwarfs fit into this scenario. Do they form like other stars do, from the collapse of giant molecular clouds? Or do they form like planets from the fragmentation of circumstellar disks?

New research in The Astrophysical Journal examined NGC 602 with the JWST and reported the first detection of a brown dwarf population outside the Milky Way. It’s titled “Discovering Subsolar Metallicity Brown Dwarf Candidates in the Small Magellanic Cloud.” The lead author is Peter Zeidler of AURA/STScI for the European Space Agency.

Brown dwarfs are sometimes called planetars or hyperjovians because they’re more massive than planets but not massive enough to be stars. They’re also often called sub-stellar mass objects. For some reason, during formation, they fail to attract enough mass to trigger fusion and become full-blown stars. Identifying them in a low-metallicity environment is a chance to understand brown dwarfs and star formation in general in a different environment.

An artist’s conception of a brown dwarf. Brown dwarfs are more massive than Jupiter but less massive than the smallest main-sequence stars. Their dimness and low mass make them difficult to detect. Image: By NASA/JPL-Caltech (http://planetquest.jpl.nasa.gov/image/114) [Public domain], via Wikimedia Commons

“Only thanks to the incredible sensitivity and resolution in the right wavelength range we are able to detect these objects at such great distances,” shared lead author Zeidler. “This has never been possible before and also will remain impossible with telescopes on the ground for the foreseeable future.”

“Until now, we’ve known of about 3000 brown dwarfs, but they all live inside our own galaxy,” added team member Elena Manjavacas of AURA/STScI for the European Space Agency.

The Hubble space telescope played a role in this work, and it’s not the first time the pair of space telescopes have created valuable scientific synergy by working together.

“This discovery highlights the power of using both Hubble and Webb to study young stellar clusters,” explained team member Antonella Nota, executive director of the International Space Science Institute in Switzerland and the previous Webb Project Scientist for ESA. “Hubble showed that NGC602 harbours very young low-mass stars, but only with Webb can we finally see the extent and the significance of the substellar mass formation in this cluster. Hubble and Webb are an amazingly powerful telescope duo!”

The researchers found 64 brown dwarf candidates in the cluster. They ranged from 0.05 to 0.08 solar masses (50-84 Jupiter masses) and are co-located with main sequence stars. The low stellar density in the cluster helped the JWST resolve individual objects. The observations are important for studying the sub-solar mass function at low metallicities.

These figures from the research illustrate some of the observations. The black circles show the region of the NGC 602 cluster, while the blue circles show the control field. The top panel shows pre-Main Sequence (PMS) stars in red circles, while the candidate brown dwarfs (cBD) are shown in yellow diamonds. The bottom panel candidate young stellar objects (cYSO) in green. PMS stars and cBDs have the same distribution, while the cYSOs are mainly located on the gas and dust ridges. Image Credit: Zeidler et al. 2024.

The concept of the Initial Mass Function (IMF) is central to star formation theory. It’s like a recipe that tells us how many stars of different masses will form in a star-forming region. The IMF usually follows a power law, meaning that more low-mass stars will form than higher-mass stars. It generally features a broad peak centred at the mass of the mean mass star.

Usually, stars lower than one stellar mass make up about 70% of the initial mass budget in a region. But even small deviations in the mean mass can have large effects on the evolution of a star cluster. Stellar radiation from young stars can affect the mean mass by raising the temperature of the star-form gas. There’s some evidence that the mean mass shifts to higher masses when the initial temperature is higher.

The data from this work shows that the low-mass objects in NGC 602 are well below the characteristic mass. The brown dwarfs have masses between 0.048 and 0.08 solar masses or 50 and 84 Jupiter masses. Since these brown dwarfs are co-located with the cluster’s young pre-Main Sequence Stars, it suggests they formed synchronously. This indicates that the stellar mass function continues into the substellar mass regime.

This image shows roughly where the studied region is in NGC 602. Image Credit: ESA/Webb, NASA & CSA, P. Zeidler, E. Sabbi, A. Nota, M. Zamani (ESA/Webb)

Unlike other similar research, the team was able to accurately measure the ages of the brown dwarfs. Typically, it’s difficult to study the IMF below the hydrogen-burning limit because objects without fusion are constantly cooling down. That makes it difficult for astronomers to estimate an object’s mass because the effective temperature keeps changing.

But by finding these brown dwarfs co-located with hydrogen-burning stars, Zeidler and his co-researchers found a way around the problem. It shows that the brown dwarfs are roughly the same age as the stars. That means the brown dwarfs and the main sequence stars all provide insight into the IMF and the sub-stellar IMF.

This figure from the research shows the radial distribution of the PMS stars (red), candidate Young Stellar Objects (green), and cBDs (yellow) within the inner 60” from the cluster center. The main sequence stars and brown dwarfs are co-located and similarly distributed, while the YSOs are less concentrated in the center of the cluster. Image Credit: Zeidler et al. 2024.

This first study is just their first step, and they intend on digging deeper.

“The accurate selection of ages, together with the superb sensitivity and calibration of JWST, will allow us, in a forthcoming paper, to reliably study the substellar mass function, well below the turnover of the IMF,” the authors write.

It’s all aimed at understanding how brown dwarfs form. If they can study the sub-stellar IMF in detail, they can determine whether it’s a continuation of the stellar IMF. Then, the researchers can answer an important unanswered question: do these objects form from the fragmentation and collapse of giant molecular clouds like stars do? Or do they form from the fragmentation of circumstellar disks like planets do?

As of now, they have only a partial answer.

“From this work, the colocation with the PMS suggests that the formation channel of the cBDs is the same as the one for their more massive stellar counterparts, as expected from solar neighbourhood studies: the fragmentation and collapse of the GMC,” the authors conclude.

The post The Webb Discovers a Rich Population of Brown Dwarfs Outside the Milky Way appeared first on Universe Today.

U.S. Naval Research Laboratory (NRL) imaging instruments on three sun-orbiting observatories have captured sequences of comet C/2023 A3, known as Tsuchinshan-ATLAS, as it passed between the Earth and the Sun during the beginning of October 2024.

Since the 1960s, astronomers have theorized that the Universe may be filled with a mysterious mass that only interacts with “normal matter” via gravity. This mass, nicknamed Dark Matter (DM), is essential to resolving issues between astronomical observations and General Relativity. In recent years, scientists have considered that DM may be composed of axions, a class of hypothetical elementary particles with low mass within a specific range. First proposed in the 1970s to resolve problems in the Standard Model of particle physics, these particles have emerged as a leading candidate for DM.

In addition to growing evidence that this could be the case, researchers at CERN are developing a new telescope that could help the scientific community look for axions – the CERN Axion Solar Telescope (CAST). According to new research conducted by an international team of physicists, these hypothetical particles may occur in large clouds around neutron stars. These axions could be the long-awaited explanation for Dark Matter that cosmologists have spent decades searching for. What’s more, their research indicates that these axions may not be very difficult to observe from Earth.

The team was led by Dion Noordhuis, a Ph.D. student with the GRavitational AstroParticle Physics Amsterdam (GRAPPA) Institute, the Institute for Theoretical Physics (ITP), and the Delta Institute for Theoretical Physics at the University of Amsterdam (UvA). He was joined by researchers from Princeton University’s Center for Theoretical Science (PCTS), the University of Barcelona, and the Rudolf Peierls Centre for Theoretical Physics at the University of Oxford. The paper that describes their findings was published on October 17th, 2024, in the journal Physical Review X.

Like DM, the existence of axions was postulated to address gaps in our understanding of the behavior of another elementary particle—the neutron. However, also like DM, these hypothetical particles have not yet been detected after decades of investigation. This is understandable since, if such particles exist, they would be extremely light, making them very hard to detect through experiments or astronomical observations. This is why axions are considered a promising candidate to explain DM, which theoretically accounts for 85% of matter in our Universe.

While DM is theorized to interact with visible matter via gravity, this does not necessarily mean that it has no other interactions that could be detectable. For example, axions are expected to convert into photons when exposed to electric and magnetic fields, which we can observe. However, the corresponding interaction strength and the amount of light produced should be very small. Therefore, they would likely go unnoticed unless there were an environment containing massive clouds of axions in a very strong electromagnetic field.

This led Noordhuis and his team to consider neutron stars since they are the densest class of stars in the Universe and generate very powerful electromagnetic fields. In fact, neutron stars generate magnetic fields that are billions of times stronger than Earth’s magnetosphere. What’s more, astronomers have used supernovae and cooling neutron stars for some time to constrain the properties of axons, including their mass and interactions with other particles. Recent research also supports the idea that their powerful magnetic fields allow neutron stars to produce huge amounts of axions near their surfaces.

In a previous study, Noordhuis and his colleagues investigated how axions could escape from a neutron star. This included computing the number of axions produced, which trajectories they would follow, and how their conversion into light could lead to an observable signal. In their latest work, the researchers focused on the axions theoretically captured by a neutron star’s gravity. Due to the very weak nature of their interactions, these particles will likely remain bound to their stars for millions of years.

Artist’s impression of an axion cloud around a neutron star. Credit: UvA

As they argue in their paper, they would gradually form a hazy cloud around the neutron star that could be visible to telescopes. The team also studied the formation, properties, and evolution of these axion clouds and found that (accounting for a wide range of axion properties) they would likely form around most, or even all, neutron stars. They also calculated that these clouds would be up to twenty orders of magnitude larger than local DM densities, producing powerful observational signatures.

These could come in the form of a continuous signal emitted during much of a neutron star’s life or as a one-time burst of light at the end of its life. These signatures would be detectable by current radio telescopes and could be used to probe the interaction between axions and photons. While no axion clouds have been observed yet, the team’s study offers astronomers parameters on what to look for. In addition to searching for axion clouds, this research presents additional opportunities for further theoretical research.

This includes follow-up work by one of the study’s co-authors on how the axion clouds can change the dynamics of neutron stars themselves. There’s also the possibility of exploring the numerical modeling of axion clouds to further constrain what and where astronomers should be looking. Finally, the present paper addresses single neutron stars, but there are also possibilities for binaries consisting of two neutron stars and a neutron star with a black hole companion. Taking advantage of next-generation instruments, in addition to current ones, these observations could be a step toward finding the elusive DM particle.

These studies could also have applications in other fields of research, such as particle physics, astrophysics, plasma physics, and radio astronomy. In short, this latest study presents opportunities for cross-disciplinary research that could resolve some of the greatest mysteries in astronomy and cosmology today.

Further Reading: University of Physics

The post White Dwarf Stars May be Shrouded in Extremely Light Particles Called Axions appeared first on Universe Today.

Some of the most cataclysmic and mysterious events in the cosmos only reveal themselves by their gravitational waves. We’ve detected some of them with our ground-based detectors, but the size of these detectors is limited. The next step forward in gravitational wave (GW) astronomy is a space-based detector: LISA, the Laser Interferometer Space Antenna.

When dense objects like black holes and neutron stars orbit each other and merge, they create gravitational waves. These ripples in space-time, which Einstein predicted in 1915, were observed for the first time in 2015 by LIGO (Laser Interferometer Gravitational-Wave Observatory). Now, we’ve observed dozens of them.

Ground-based detectors like LIGO have two long “arms” at right angles to each other. A powerful laser beam is split into two identical beams that travel down each arm, or tunnel, that are several kilometres apart. The beams are reflected back and forth by mirrors at the ends of the arms, and when they combine, they interfere with each other. Whenever a GW passes through Earth, it warps spacetime. That makes one arm longer than the other, which changes the interference pattern in the beams.

The Laser Interferometer Gravitational-Wave Observatory is made up of two detectors, this one in Livingston, La., and one near Hanford, Wash. The detectors use giant arms in the shape of an “L” to measure tiny ripples in the fabric of the universe. Credit: Caltech/MIT/LIGO Lab

The length of the arms limits the sizes of the GWs LIGO can detect and also limits the type of mergers it can detect. It can only detect higher-frequency GWs from 10 to 1,000 Hertz, which come from merging pairs of black holes (BH), merging pairs of neutron stars (NS) and merging mixed pairs of BHs and NSs.

LISA will be much different. It doesn’t have the same arm-length limitation. LISA will be the first dedicated space GW observatory, and it will consist of three separate spacecraft arranged in an equilateral triangle. Each spacecraft will be 2.5 million km apart, meaning LISA’s arms will be 2.5 million km long.

An artist’s concept of how LISA will work to detect gravitational waves from orbit in space. Courtesy ESA.

The ESA/NASA LISA mission is the next step in gravitational wave (GW) astronomy. With its much longer arms, LISA will detect low-frequency waves from 0.1 mHz to 1 Hz and expand our search for GWs and the events that create them. It’ll detect GWs from other sources, like supermassive black hole (SMBH) mergers, binary white dwarf systems, and Extreme Mass Ratio Inspirals (EMRIs). (EMRIs are systems where objects like a stellar-mass black hole or a white dwarf spiral into an SMBH.)

Like LIGO, LISA will also be a laser interferometer. Any change in its laser interference pattern can be attributed to a GW. However, LISA will do more than just detect GWs. It can determine other characteristics in the complex GW waveforms, like black hole spin.

NASA is busy working on the mission, which isn’t scheduled to launch until 2035. They’ve given us our first look at a full-scale prototype of the six cameras LISA will rely on.

“Twin telescopes aboard each spacecraft will both transmit and receive infrared laser beams to track their companions, and NASA is supplying all six of them to the LISA mission,” said Ryan DeRosa, a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The prototype, called the Engineering Development Unit Telescope, will guide us as we work toward building the flight hardware.”

On May 20, the full-scale Engineering Development Unit Telescope for the LISA (Laser Interferometer Space Antenna) mission, still in its shipping frame, was moved within a clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. They’re made of an amber-coloured glass ceramic called Zerodur that resists changes over a wide range of temperatures. The telescopes also feature a thin layer of gold on their surface. Image Credit: NASA/Dennis Henry

The telescopes are made to be stable over a wide temperature range since precision is key to success. They need to detect changes as small as picometers, or trillionths of a meter, between each spacecraft. Unlike LIGO, the three spacecraft that make up the system cannot be kept at precise distances from one another. Over each year’s orbit, the distance between them changes significantly, and the system has to track the changes to guarantee precision.

The thin layer of gold is highly reflective in the infrared range that LISA’s lasers will use. It also minimizes thermal absorption and provides consistent reflectivity over long periods of time. Gold also resists corrosion, protects the underlying layer from degradation, and is thermally stable.

LISA has another trick up its sleeve: free-floating cubes or test masses. They reflect the lasers back and forth between the spacecraft and are a critical part of its detection system. They’re 46mm solid cubes made of gold-platinum alloy that weigh approximately 2 kg each. The cubes are extremely pure and will have a homogeneous material composition. They’ll float freely inside electrode housings within each spacecraft. The cubes serve as reference points for GW measurement.

The ESA and NASA have already tested some of LISA’s components in space. In 2015, the ESA launched the LISA Pathfinder mission. It tested a much smaller version of one of LISA’s arms and also tested the cubes. It placed two test masses in a near-perfect gravitational free-fall and controlled and measured their motion with unprecedented accuracy.

This image shows the interior layout of LISA Pathfinder’s science module. The test masses are visible in the centre of the image. Image Credit: ESA/ATG medialab. LICENCE: ESA Standard Licence

We’ve come a long way since Einstein predicted gravitational waves. When the first one was detected in 2015, it opened a new window into the cosmos.

LISA will throw that window wide open and reveal galaxy-defining events like supermassive black hole mergers.

The post NASA is Building Telescopes for the LISA Mission appeared first on Universe Today.

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